Coupling assembly

ABSTRACT

A railway coupling assembly including an insert having a first portion which operably receives draft forces transmitted from a coupler bar through a coupler pin. A second portion of the insert distributes draft forces to a yoke and reduces the intensity of stresses developed therein. A third portion of the insert reduces the magnitudes of moments developed in the coupler pin.

United States Patent June 10, 1975 Farris [54] COUPLING ASSEMBLY 3.635.358 1/1972 Altherr 213/69 3,720,325 3 1973 St'tk 213 69 X [751 lnvemo" Richard Farris! Joshua 3,760,954 91973 Hers ey 2 13/69 [73] Assignee: l-lalliburton Company, Duncan,

Okla. Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-Gene A. Church [22] July 1974 Attorney, Agent, or Firm-John H. Tregoning Appl. No.: 491,950

[52] US. Cl 213/69; 213/67 [51] Int. Cl. B6lg 9/00 [58] Field of Search 213/62, 64, 67, 69, 68, 213/505 [56] References Cited UNITED STATES PATENTS 3,042,224 1/1962 Blattner 213/68 X 3,635,357 1/1972 Altherr 213/69 X ABSTRACT A railway coupling assembly including an insert having a first portion which operably receives draft forces transmitted from a coupler bar through a coupler pin. A second portion of the insert distributes draft forces to a yoke and reduces the intensity of stresses developed therein. A third portion of the insert reduces the magnitudes of moments developed in the coupler pin.

9 Claims, 6 Drawing Figures PATENTEDJUH I 0 ms '5 SHEET -lllk llllttlll a! l IIII'IIIIIIIII COUPLING ASSEMBLY BACKGROUND AND BRIEF SUMMARY OF THE INVENTION The present invention relates to an improved coupling assembly for a railway vehicle. More particularly, the invention relates to an insert which, as a part of a coupling assembly, receives and distributes to a main body portion of the coupling assembly forces exerted through a coupler pin by the shank of a coupler bar when a railway vehicle is undergoing draft forces. The insert also serves to reduce the magnitudes of moments developed in the coupler pin during draft loading.

Since emerging in the last half of the nineteenth century as an efficient mode of transportation, railroads have been employed to convey a major portion of the goods involved in national and international commerce. This may be due in large part to the fact that railroad transportation provides an ideal method for transporting goods long distances overland. Large quantities of goods, including materials far too heavy for transportation by truck, can be carried and dispersed through a vast network of railroads by the simple expedient of uncoupling and switching to different trains, cars carrying a particular cargo.

In order to facilitate the dispersion of individual carloads of goods through the railroad network, most distribution centers have large freight yards in which railway vehicles can be loaded, coupled, switched, and unloaded. Typically, a railway vehicle is loaded with a finished product or with raw materials in a particular part of the freight yard or on a loading spur leading into the freight yard. Once the railway vehicle is loaded, it may be coasted r, coupled to a switching locomotive and, drawn onto a different track where a train which is to travel toward the desired destination of the railway vehicle is being made up.

It may be that the ultimately desired destinations of the various cars in the train are somewhat divergent. If this is the case, each car will in all likelihood pass through a number of intermediate freight yards where the car is uncoupled and switched to another train. Ultimately, through the uncoupling, switching, and coupling process the car originally loaded in a distant freight yard or on an associated loading spur becomes a part ofa train which travels to the desired destination.

The process outlined in the preceding is achievable in material part through the provision of coupling as semblies which are employed in connecting modern railway vehicles together. Such assemblies normally in clude a coupler bar comprised of a coupler head and an elongated shank depending therefrom. The shank, in one form of assembly known as an F-type coupler, is pivotally connected through a circular cylinder cou pler pin to a part of a railway vehicle. In this construction the coupler pin is vertically oriented and is normally carried by a yoke. The open end of the yoke embraces the end of the coupler shank most distal from the coupler head. This arrangement permits the coupler bar to pivot in a horizontal plane to accommodate movement of a series of railway vehicles along curved segments of track. All of the load which is applied to a railway vehicle by a locomotive is applied through the coupler bar and, in draft, the entire load is sustained by the coupler pin and the associated supportive yoke.

At each stage in the movement of a railway vehicle as set forth in the preceding, and in particular when the loaded railway vehicle is at rest and is then set in motion by a locomotive, considerable impact loads may be applied to the coupler bar, yoke and coupler pin. If, for instance, the railway vehicle is set in motion by the application of draft forces, this impact loading is transmitted directly from the shank into the coupler and from the coupler pin into the yoke carrying the pin. Since the coupler pin bears against the yoke during draft, sudden and rather large stress concentrations may be developed therein by virtue of the abrupt character of the loading and the circular cylinder configuration of the pin. Similarly, since the coupler pin is normally restrained only at opposite ends by the legs of the yoke, and since the coupler shank normally acts upon a central portion of the coupler pin, relatively large bending stresses may be developed in the pin. Over the useful life ofa railway vehicle, the magnitude and cyclic character ofthe stresses introduced into the coupler pin and yoke may render these members subject to considerable wear.

At least two further effects which may significantly contribute to the problem of wear and possible failure of coupling assemblies may be encountered by a railway vehicle as the train rolls between various terminal or freight yards.

One of these effects is that of impact loadings of the coupler pin and yoke due to phenomena commonly termed train action events." Train action events may be defined as phenomena which occur as a consequence of the existence of slack in the couplings between moving railway vehicles. Such slack enables the vehicles to undergo relative movement while in motion on a rail bed. A train action event is termed a run-out where adjacent vehicles are moving apart. Where moving vehicles are moving together, the train action event is termed a run-in." As the railway vehicles move rela tive to one another, the speed of the vehicles equalizes. This equalization is commonly termed train action.

At the termination of train action events, shock forces may be transmitted in a wave throughout the train through the coupling assemblies of the vehicles. Those shocks which occur during and upon termination of run-out may be severe enough to introduce damaging stress concentrations and undesirable wear patterns in the pin and yoke connecting the coupler bar to the railway vehicle. As in the case of the impact draft loads occurring incident to switching operations, train action may cause the pin and yoke of a coupling assembly to readily wear.

A second effect may be the exertion of impact loading on a coupler pin and yoke due to irregularities in the track of the rail bed. As the train is moved along the rail bed, rough or spring areas of track may be encountered. Perhaps the most notable form of roughness is that due to joints in the track. These rough areas periodically add to the total drag acting on the train and result in an increase in the loading of the coupler pin and yoke of the railway vehicle. As in the case of the load ing introduced by train action events, the cyclic impact loading resulting from increased drag may introduce undesirable stresses and stress concentrations in the pin and yoke. As before, these stresses may subject the pin and yoke to considerable wear.

Some attempts have been made in the prior art to diminish the tendency of the yoke to wear in the course of the ordinary use of the railway vehicle. In this connection it appears that one approach taken to prevent undue wear of the yoke has been to line the aperture holding the coupler pin with a sleeve which has been appropriately machined. The sleeve is commonly heat treated to render it somewhat harder than the casing which forms the yoke. The sleeve is normally of the same general shape as the coupler pin which fits within the sleeve An arrangement of this type, though it may be of some use in preventing or minimizing wear, nonetheless leaves the yoke as vulnerable as before to the effects of impact loading. The impact loads are simply transmitted from the coupler bar into the pin and ultimately directly into the yoke with the level of stress remaining undiminished.

Further, a sleeve of the type discussed in the preceding must normally be machined to relatively close tolerances. Similarly, the aperture in the yoke which is to receive the sleeve must also be machined to relatively close tolerances. Normally a yoke employed to carry a coupler pin is quite large; thus. machining of the yoke may entail handling a highly cumbersome article. The difficulty encountered in handling the yoke may render the machining to the desired tolerances at least difficult and certainly costly.

A further disadvantage resides in the manner in which the sleeves of the prior art are often installed within the apertures of the yokes. A sleeve may be installed either by expanding the aperture in the yoke to hold the sleeve or by shrinking the sleeve. Once the sleeve is inserted, the aperture or sleeve can be allowed to return to its original size with the result that the sleeve is tightly held within the aperture. The expansion of the aperture or the shrinkage of the pin is normally accomplished by exposing either the yoke or the pin to a suitable temperature extreme. When the yoke or pin is no longer exposed to this temperature extreme the aperture or sleeve can return to its original size. Alternatively, a sleeve may also be installed by forcing it into aperture of the yoke. In this case, the sleeve and aperture are normally machined so that the sleeve is slightly larger in diameter than the aperture. The sleeve is placed over the mouth of the aperture and a suitable press is employed to force the sleeve to a desired position within the aperture.

Several significant disadvantages inhere in both of the foregoing assembly techniques. Normally both methods require that the sleeve and the aperture to be lined be machined to rather close tolerances. As suggested in the preceding. this machining is often costly or difficult or both. Furthermore, neither method is particularly well suited to application in the field. It may be necessary in either case to disassemble significant portions of the coupling assembly and considerable amounts of cumbersome and/or expensive equipment may be necessary. Additionally, both methods may be tedious and time consuming. Of independent significance is the fact that no evidence has been noted regarding an attempt in the past to reduce bending stresses in the coupling pin.

The problems suggested in the preceding are not intended to be exclusive but rather are among many which may tend to reduce the effectiveness of coupling assemblies of the prior art. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that coupling assemblies appearing in the prior art have not been altogether satisfactory. A coupling assembly according to the present invention is intended to obviate or at least minimize problems of the type previously described.

A coupling assembly according to the present invention includes a sill which extends along the underframing of a railway vehicle and a coupler bar. including a coupler head and an elongated shank. which extends into a forward portion of the sill. The end of the shank opposite the coupler head is apertured and is pivotally connected through a circular cylinder coupler pin to a yoke having forwardly extending legs apertured to receive and carry the coupler pin. The yoke serves to operably interconnect the sill and the apertured end of the coupler shank. The forwardmost portion of the aperture of each leg is enlarged and is bounded in part by a vertically planar bounding surface which is perpendicular to the longitudinal axis of the leg. Disposed within a forward portion of the aperture of each leg is an insert a portion of which receives forces transmitted from the coupler bar through the coupler pin while the railway vehicle is undergoing draft forces. A second portion of the insert distributes these forces over the vertically planar boundary surface of the aperture of the leg to reduce the intensity of stresses developed therein. A third portion of the insert reduces the magnitudes of moments developed in the coupler pin.

THE DRAWINGS A preferred embodiment of the invention is illustrated in the appended drawings wherein:

FIG. 1 illustrates an exploded perspective view of the operative environment of the invention;

FIG. 2 illustrates a partially exploded perspective view of a yoke and an insert of a coupler assembly according to the present invention;

FIG. 3 illustrates a longitudinal, vertical sectional view taken along section line 33 of FIG. 2 and further illustrates a coupler pin and shank in place in the yoke;

FIG. 4, note sheet 3, illustrates a horizontal sectional view taken along section line 44 of FIG. 3;

FIG. 5 illustrates a vertical sectional view taken along section line 5-5 of FIG. 4; and

FIG. 6, note sheet 2, illustrates a perspective view of an insert according to the present invention employed to protect the yoke of the coupler assembly.

DETAILED DESCRIPTION Context of the Invention Referring particularly to FIG. I, an exploded perspective view can be seen of a general operative environment of the invention.

Normally railway vehicles such as that illustrated at 10 are interconnected by coupling assemblies such as that generally illustrated at 12. The coupling assembly 12 is operably connected to the underframing of the railway vehicle. As illustrated, this underframing may be comprised of a heavy cross brace 14 having a central aperture 16 intended to receive and pivotally retain a pin extending upwardly from a central portion of a railway truck. For convenience and simplicity the truck and upwardly extending pin are not illustrated.

A part of the underframing of the railway vehicle is also formed by a sill 18 which provides a housing within which the coupling assembly 12 extends. The sill 18 forms an elongated channel and is comprised of suitable walls 20 which may terminate at one end with the cross member 14 and at the other with splayed walls 22 which form a mouth 24 of the sill 18. The splayed walls 22 permit the coupler bar to pivot in a horizontal plane as will be described more fully in the course of subsequent discussions.

The coupling assembly, in one embodiment, may be comprised of hydraulic cylinder 26 which may terminate at the forwardmost end thereof with a yoke 28. A coupler bar, including a coupler shank 38 and coupler head 40 operably extends within the sill l8 and is connected to the yoke 28.

In conjunction with a similar coupler bar connected to an adjacent railway vehicle, the coupler head 40 is employed to effect the actual mating and coupling of the railway vehicles together. The end or butt of the coupler shank 38 opposite the coupler head 40 is fashioned with an aperture 42 which passes vertically through the shank. The butt of the coupler shank is rounded as at 44 for a purpose to be more fully discussed later. The yoke 28 and the coupler shank 38 are connected together by means ofa coupler pin 46 which passes through the aperture 42 in the coupler shank and is retained in apertures 48 disposed in the yoke 28. As is readily apparent from FIG. 1, the coupler pin 46 is vertically oriented and the coupler bar is thus free to pivot about the pin 46 in a horizontal plane.

As suggested, the cushioning unit illustrated in FIG. 1 functions to at least partially isolate the railway vehicle from draft and buff impact loads imparted to the yoke 28 by the coupler head 40 and the coupler shank 38. In this connection piston rod 30 extends from the end of the hydraulic cylinder opposite the yoke 28 and terminates in bearing 32. The bearing 32 is normally anchoged to the underframing of the railway vehicle by means of a bearing housing 36 which is connected within the sill 18. The end of the piston rod 30 opposite the bearing 32 carries a piston head 34.

The combined hydraulic cylinder 26, piston rod 30, and piston head 34 function together as a damper or cushioning unit to at least partially isolate the railway vehicle 10 and its contents from impact loads received by the yoke 28.

Extension of the cushioning unit is limited by draft stops 50 which are connected to the interior of the elongated channel formed by the sill 18. The draft stops 50 are engaged by suitable flanges 52 which at least partially surround the coupling assembly intermediate the hydraulic cylinder 26 and the yoke 28. Similarly, the contraction of the cushioning unit is limited by the bearing housing 36 which, like the draft stops 50, are connected to the interior of the elongated channel formed by the sill 18.

Regardless of whether the coupling assembly 12 responds to buff or draft loading, the cushioningunit formed by the hydraulic cylinder 26, the piston rod 30, and the piston 34 must be restored from a contracted or extended condition to its normal, neutral configuration so that a subsequent impact load can be properly cushioned. To this end, a restoring device 56 is provided to resiliently urge the cushioning unit back to its neutral position after the coupling assembly is no longer loaded or the loading has been reduced to a level at which it can be overcome by the restoring device.

The restoring device 56 is connected to the sill 18 by means of a base plate 58 which spans the sill and may be comprised of a system of coil springs 60. At least one of these springs may be connected to a connecting fixture 62 which is in turn rigidly connected to the yoke 28.

A more complete disclosure of a hydraulic cushioning unit such as outlined above may be had by reference to Seay, et al., US. Pat. No. 3,589,527 issued June 29, l97l and assigned to the assignee of the subject application. The disclosure of this Seay et al patent is hereby incorporated by reference as though set forth at length.

It should be emphasized however at this point that a number of different cushioning units are employed in the railroad industry such as resilient and friction draft gears, and that the particular configuration discussed herein is exemplary only.

Yoke Assembly The particular manner in which the yoke 28, the coupler shank 38, and the coupler pin 46 interact can be best appreciated upon examination of FIGS. 3 and 4. It can be seen from both figures that each aperture 48 in the yoke 28 is essentially'elliptical. It can also be seen that a buff pad 64 may be located behind the butt end of the coupler shank 38 in close proximity therewith. The buff pad 64 is positioned between the rounded butt end 44 of the coupler shank and a crotch 66 formed between the upper leg 68 and the lower leg 70 of the yoke 28. Because the buff pad 64 is so closely positioned relative to the rounded butt end 44 of the coupler shank 38, and because the major axis of the elliptical aperture 48 is considerably larger than the di ameter of the coupler pin 46, the coupler pin is not loaded by buff loading on the coupler bar. Rather, the rounded butt end 44 of the coupler shank 38 bears directly against the buff pad 64. The buff pad in turn distributes the load into the crotch 66 between the legs of the yoke 28. In draft, the situation is reversed and draft loads exerted on the coupler bar are received directly by the coupler pin 46. The coupler pin in turn transfers the load into each leg of the yoke 28.

Referring now to FIGS. 2 through 5, the yoke struc ture per se can be appreciated in detail. As is readily apparent from any of the illustrations mentioned, the yoke 28 extends forwardly from the hydraulic cylinder 26 to embrace the end of the coupler shank 38 opposite the coupler head 40. The yoke is formed by an upper and a lower leg 68 and 70, respectively, both of which are essentially planar and mutually parallel. The legs are spaced somewhat apart and are joined adjacent the hydraulic cylinder by a crotch 66.

Intermediate the crotch 66 of the yoke and the ends of the legs opposite the crotch are two vertical bracing members 72 which extend between the two legs. The surfaces of the bracing members facing outwardly from the interior of the yoke are essentially planar and generally merge in a coplanar manner with the lateral edges of the legs. The surfaces of the bracing members facing inwardly toward the interior of the yoke are arcuate. This configuration is perhaps best illustrated by the broken lines appearing in FIG. 4 and is provided to accommodate pivoting motion of the coupler bar,

A fixture 62 is connected to a lowermost surface of the lower leg 70 in a central portion thereof and serves to connect the yoke to the restoring device 56 illustrated in FIG. 1. Also connected to the york generally intermediate the crotch 66 and the hydraulic cylinder 26 are flanges 52 which engage draft stops 50. As indicated, the flanges serve to limit the extent to which the eushioi q unit formed by the hydraulic cylinder 26, the piston rod 30, and the piston 34 can extend.

Coupler Pin and Apertures With renewed attention to FIGS. 2 through 5, the coupler pin 46 and the apertures 42 and 48 through the coupler shank and yoke. respectively, can be seen in more detail.

As illustrated in FIGS. 3 and 4, the coupler pin 46 is comprised of a solid circular cylinder which is vertically oriented. The coupler pin extends through the aperture 42 in the coupler shank and the apertures 48 in the yoke. The coupler pin thus connects the yoke 28 and the coupler shank 38 so that the draft forces can be exerted by the coupler bar on each leg 68 and 70 of the yoke 28 and so that the shank 38 can freely pivot in a horizontal plane about the longitudinal axis of the coupler pin.

As suggested in the course of earlier discussion, the apertures 48 in the legs of the yoke take a generally elliptical configuration when the coupling assembly is fully assembled. In this regard an insert to be discussed hereinafter must be installed to form a part of the elliptical periphery of the aperture. An elliptical aperture is provided so that the coupler pin will not be subject to buff loading. Buff loading is transmitted from the coupler shank 38 through the rounded butt end thereof directly into the buff pad 64.

In a disassembled condition, i.e., without the insert to be discussed in the next section, each aperture takes on a more complicated configuration. As perhaps best illustrated in FIG. 4, it can be seen that each aperture is bounded by a semicircular rearmost surface 74 which is tangentially joined at either end by planar, forwardly extending, essentially parallel side surfaces 76.

Each aperture is enlarged from an elliptical configuration and is further bounded by a plurality of surfaces which combine to form a transverse, rectangular receptacle 78 which intersect the side surfaces 76 in an essentially orthogonal manner. One of these surfaces forms a vertically planar, forwardmost bounding surface 79 which is orthogonally oriented relative to the longitudinal axis of the leg of the yoke.

The receptacle 78 narrows in a single stage as it passes through each leg of the yoke 28. The particular manner in which the receptacle narrows can perhaps best be seen in FIG. 5. In this figure it will be noted that in each leg the receptacle extends downwardly through most of the thickness of the leg and then narrows considerably in a single stage as it continues through the leg. The narrowing of the receptacle 78 thus provides a shelf 80 in each leg which serves to support an insert.

It can also be appreciated from an examination of FIGS. 2 through that the aperture in each leg of the yoke is also bounded by a shallow recess 82 formed in the upper surface of each leg adjacent the forwardmost portion of the receptacle 78. This recess or slot is fashioned with a generally rectangular configuration and is intended to receive a retaining key.

Insert and Retaining Key for Apertures of the Yoke As suggested in the preceding section, each elliptical aperture 48 is formed in part by an insert 84. The insert 84 is illustrated in FIGS. 2 through 6 but can perhaps be best seen in FIG. 6.

Referring initially to FIG. 6, it will be appreciated that each insert 84 is comprised of an arcuate force recciving portion 86 against which the coupler pin bears when the coupling assembly is subjected to draft forces. Arcuate lingers 88 serve to extend the force receiving portion and. as perhaps best illustrated in FIG. 4, serve to complete the generally elliptical aperture 48 provided in each leg of the yoke. By interposing this force receiving portion between the yoke and the coupler pin, the yoke can be protected from undue wear.

By virtue of the small size of the insert. it can be readily heat treated to a desired hardness and forged to close tolerances. Increased hardness of course tends to reduce wear. The close tolerances permits more intimate contact between the various bearing surfaces. In particular, the force receiving portion of each insert can be intimately contacted by the coupler pin and less time is required for wear in.

Connected to the force receiving portion of the insert 84 is an essentially planar force distributing portion 90. As can perhaps best be seen in FIG. 2, the force distribution portion 90 is characterized by a planar bearing surface 92 which is symmetrically oriented relative to the arcuate surface bounding the force receiving portion 86. It should be noted that the bearing surface 92 faces in a direction opposite that of the arcuate surface bounding the force receiving portion. This relation can perhaps best be seen in FIG. 4.

It will be noted from FIG. 6 that the ends 94 of the force distributing portion of the insert 84 extend laterally considerably beyond the arcuate fingers 88 of the force receiving portion of the insert. This configuration permits the area of the bearing surface 92 to be enlarged so that forces received by the force receiving portion of the insert can be distributed into the vertically planar bearing surface 79 and stress concentrations thereby reduced. This configuration also affords an advantageous mode of carrying an insert within the aperture of a leg of the yoke. The force receiving portion of the insert 84 can simply be inserted in the receptacle 78 of a leg of the yoke until the lowermost surface of the force receiving portion of the insert rests on the shelf 80 formed by the narrowing of the receptacle. In this way each insert is carried within the aperture of a leg and is properly positioned to intimately receive the coupler pin against the force receiving portion thereof.

An insert 84 can be safely retained within the aperture of a leg by means ofa retaining key 96. The retaining key is perhaps best illustrated in FIG. 2 and takes a generally C-shaped configuration. Once an insert is installed within the aperture of a leg of the yoke, the retaining key 96 can be placed in the recess 82 and welded as at 98 around substantially the entire periphcry of the recess.

Referring again to FIG. 6, it will be noted that the force receiving portion and the force distributing portion of each insert extends upwardly to form a roughly C-shaped boss 100. This boss serves to reduce the magnitude of moments developed in a coupler pin as it bears against the force receiving portion of the insert when the coupling assembly is being subjected to draft forces.

Referring to FIG. 5, it can be appreciated that the inserts 84 are inserted within the apertures 48 in such a manner that the bosses 100 extend inwardly toward the interior of the yoke 28. This inward projection of the bosses 100 can also be seen in FIG. 3 and in addition the manner in which the bosses diminish the magnitudes of moments developed in the coupler pin can be appreciated. I

More particularly the bosses 100 project inwardly toward the interior of the yoke, the distance which the coupler pin must span in passing from one leg of the yoke to the other is diminished. Thus the magnitudes of moments developed by virtue of the exertion of draft forces by the coupler bar are reduced.

Once the inserts are inserted in the apertures in the legs of the yoke and the retaining key of each aperture is welded in place. the coupler pin 46 can bear directly against the force receiving portion of each insert. The forces exerted on the insert by virtue of this relation are transmitted into the force distributing portion thereof and are distributed into each leg of the yoke through the planar bearing surfaces 79 and 92. This permits forces which otherwise would be rather concentrated and exerted near the forwardmost portions of the apertures in the yoke to be distributed over a larger area. Thus, while the total force is not decreased, the bearing forces which may tend to deform or wear the aperture in each leg of the yoke are diminished.

From the foregoing it should now be appreciated that in distributing the forces exerted by the coupler bar through the coupler pin, undesirable stress concentrations and attendant wear and/or fatigue can be reduced. Similarly, since the magnitude of moments developed in the coupler pin are reduced, smaller bending stresses are introduced into the coupler pin and the pin is less subject to the fatigue or wear which may occur as a result of cyclic flexure.

It is noteworthy that either one or both of the inserts can be readily replaced in the field should they become worn or otherwise damaged. As suggested earlier, each insert is simply slipped within the aperture of a leg of the yoke and is carried therein by virtue of its projection into the receptacle which forms a part of the aperture. Once the insert is slipped into place, the retaining key is welded into the recess adjacent the receptacle to retain the insert in place. To remove worn or otherwise damaged inserts, a cutting torch can be used to quickly remove the retaining key retaining each insert within the receptacle. The insert can be then removed and a new insert mounted in its place. Thereaftera new retaining key can be welded in place and the replacement operation completed.

SUMMARY OF THE MAJOR ADVANTAGES OF THE INVENTION In describing a coupling assembly according to the present invention, several advantages have been specifically and inherently disclosed. Nonetheless a brief summary of major advantages at this point may be both useful and appropriate.

A principle advantage of the present invention resides in the fact that wear to the yoke of a coupling assembly is reduced by interposing an insert between the coupler pin and the aperture in the york carrying the Another advantage of the present invention resides in the fact that forces transmitted to the yoke of the coupling assembly through the coupler pin are distributed over a considerable portion of the yoke to minimize undesirable concentrations of stress.

Still another advantage of the invention is that it provides an accurately contoured insert against which the coupler pin can intimately bear and which can in turn 10 intimately bear against the yoke of the coupling assembly.

A further significant advantage of the invention is that the coupler pin and the poriton of the coupling assembly against which it bears are initially in more intimate contact and therefore undergo a shorter period of wear in" during which the coupler pin seats itself.

A still further advantage resides in the fact that the portion of the coupling assembly against which the coupler pin bears during draft can be conveniently heat treated to the desired degree of hardness.

Yet still a further highly significant advantage of the invention is that the magnitudes of bending moments developed in the coupler pin incident to the exertion of draft forces are reduced.

An additional advantage resides in the fact that the insert is simple in configuration and can be given its basic form by a simple drop forging process. No costly machining of the type necessary to form a cylindrical sleeve or aperture is required.

Another highly significant advantage of the invention resides in the fact that the portion of the yoke against which the coupler pin bears during the exertion of draft forces can be readily removed and replaced in the field without cumbersome or costly equipment.

In describing the invention, reference has been made to a preferred embodiment. However, those skilled in the art and familiar with the disclosure of the invention may recognize additions, deletions, substitutions, or other modifications which would fall within the purview of the invention as defined in the claims.

What is claimed is:

1. In a coupling assembly including:

a sill connected to the underframing of a railway vehicle; a coupler bar including a coupler head and an elongated coupler shank extending into a for ward portion of the sill, one end of the coupler shank opposite the coupler head having an aperture extending therethrough; a yoke operably interconnecting the sill and the apertured end of the coupler shank, the yoke having opposed essentially parallel legs extending forwardly toward the coupler bar and coaxial apertures extending transversely through the legs; and a circular cylinder coupler pin extending through the apertures of the yoke and the aperture of the coupler shank to pivotally connect together the coupler bar and the yoke;

the improvement comprising:

a plurality of bounding surfaces forming in each leg of the yoke an enlargement of the aperture therein, one of the bounding surfaces forming a vertically planar forwardmost bounding surface of the aperture orthogonally oriented relative to the longitudinal axis of the leg; and a pair of inserts each removably mounted in a forward portion of the aperture of a leg of the yoke and including force receiving means for receiving draft forces transmitted from the coupler shank through the coupler pin; and

force distributing means connected to said force receiving means for distributing forces received by said force receiving means over the planar, forwardmost bounding surface of the aperture of the leg to reduce the concentration of forces exerted on the leg through the coupler pin.

2. The coupling assembly as defined in claim 1 wherein said force receiving means comprises:

an arcuate, essentially semicircular. rearwardly facing bearing surface having a radius of curvature essentially equal to that of said coupler pin.

3. The coupling assembly as defined in claim 2 wherein said force distributing means comprises:

a planar, forwardly facing bearing surface in intimate contact with said planar, forwardmost bounding surface of an aperture in the yoke, said bearing surface being formed with said force receiving means in an opposed. symmetrical relation therewith.

4. The coupling assembly as defined in claim 1 wherein said force distributing means comprises:

a planar, forwardly facing bearing surface in intimate contact with said planar, forwardmost bounding surface of an aperture in the yoke, said bearing surface being formed with said force receiving means in an opposed, symmetrical relation therewith.

5. The coupling assembly as defined in claim 1 wherein:

the aperture in each leg of the yoke is bounded by a semicircular rearmost surface; two planar, for wardly extending, essentially parallel side surfaces each tangentially joining an end of said semicircular surface; and said bounding surfaces of said enlargement, said bounding surfaces of said enlargement forming a rectangular receptacle which es sentially orthogonally intersects said planar surfaces and which narrows in width in a single stage as it extends through said leg; and

said force distributing means is insertable and retainable within said receptacle and thereby operably positioned in intimate contact with said coupler pin when the railway vehicle is undergoing draft forces. 6. The coupling assembly as defined in claim 5 wherein:

said force receiving means fits between said forwardly extending planar side surfaces of said aperture of a leg and, in conjunction with said semicircular rearmost surface, forms an essentially elliptical aperture for said pin. 7. The coupling assembly as defined in claim 5 wherein:

the aperture in each leg of the yoke is also bounded by a shallow recess adjacent the forwardmost portion of said rectangular receptacle; and retaining means insertable and weldable in said recess for retaining said force distributing means in said receptacle once said force distributing means is inserted therein. 8. The coupling assembly as defined in claim 1 and further comprising:

moment reducing means connected to said insert for reducing the bending moment developed in said pin by draft forces transmitted from the coupler shank into said pin. 9. The coupling assembly as defined in claim 8 wherein said moment reducing means comprises:

an inward extension of said force receiving means and said force distributing means toward the space which the coupler pin spans in extending between the legs of the yoke. 

1. In a coupling assembly including: a sill connected to the underframing of a railway vehicle; a coupler bar including a coupler head and an elongated coupler shank extending into a forward portion of the sill, one end of the coupler shank opposite the coupler head having an aperture extending therethrough; a yoke operably interconnecting the sill and the apertured end of the coupler shank, the yoke having opposed essentially parallel legs extending forwardly toward the coupler bar and coaxial apertures extending transversely through the legs; and a circular cylinder coupler pin extending through the apertures of the yoke and the aperture of the coupler shank to pivotally connect together the coupler bar and the yoke; the improvement comprising: a plurality of bounding surfaces forming in each leg of the yoke an enlargement of the aperture therein, one of the bounding surfaces forming a vertically planar forwardmost bounding surface of the aperture orthogonally oriented relative to the longitudinal axis of the leg; and a pair of inserts each removably mounted in a forward portion of the aperture of a leg of the yoke and including force receiving means for receiving draft forces transmitted from the coupler shank through the coupler pin; and force distributing means connected to said force receiving means for distributing forces received by said force receiving means over the planar, forwardmost bounding surface of the aperture of the leg to reduce the concentration of forces exerted on the leg through the coupler pin.
 2. The coupling assembly as defined in claim 1 wherein said force receiving means comprises: an arcuate, essentially semicircular, rearwardly facing bearing surface having a radius of curvature essentially equal to that of said coupler pin.
 3. The coupling assembly as defined in claim 2 wherein said force distributing means comprises: a planar, forwardly facing bearing surface in intimate contact with said planar, forwardmost bounding surface of an aperture in the yoke, said bearing surface being formed with said force receiving means in an opposed, symmetrical relation therewith.
 4. The coupling assembly as defined in claim 1 wherein said force distributing means comprises: a planar, forwardly facing bearing surface in intimate contact with said planar, forwardmost bounding surface of an aperture in the yoke, said bearing surface being formed with said force receiving means in an opposed, symmetrical relation therewith.
 5. The coupling assembly as defined in claim 1 wherein: the aperture in each leg of the yoke is bounded by a semicircular rearmost surface; two planar, forwardly extending, essentially parallel side surfaces each tangentially joining an end of said semicircular surface; and said bounding surfaces of said enlargement, said bounding surfaces of said enlargement forming a rectangular receptacle which essentially orthogonally intersects said planar surfaces and which narrows in width in a single stage as it extends through said leg; and said force distributing means is insertable and retainable within said receptacle and thereby operably positioned in intimate contact with said coupler pin when the railway vehicle is undergoing draft forces.
 6. The coupling assembly as defined in claim 5 wherein: said force receiving means fits between said forwardly extending planar side surfaces of said aperture of a leg and, in conjunction with said semicircular rearmost surface, forms an essentially elliptical aperture for said pin.
 7. The coupling assembly as defined in claim 5 wherein: the aperture in each leg of the yoke is also bounded by a shallow recess adjacent the forwardmost portion of said rectangular receptacle; and retaining means insertable and weldable in said recess for retaining said force distributing means in said receptacle once said force distributing means is inserted therein.
 8. The coupling assembly as defined in claim 1 and further comprising: moment reducing means connected to said insert for reducing the bending moment developed in said pin by draft forces transmitted from the coupler shank into said pin.
 9. The coupling assembly as defined in claim 8 wherein said moment reducing means comprises: an inward extension of said force receiving means and said force distributing means toward the space which the coupler pin spans in extending between the legs of the yoke. 